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Background <p><i>Artemisia annua</i> L., is the primary natural source of the antimalarial drug artemisinin. In nature, fluctuating light is a major environmental stress that affects plant growth and artemisinin biosynthesis. Although the light-harvesting chlorophyll a/b-binding (<i>LHC</i>) superfamily plays a key role in mediating plant responses to fluctuating light, systematic research of this gene family in <i>A. annua</i> has not yet been conducted, limiting our understanding of light adaptation in this medicinally important species.</p> Results <p>This study investigated the evolutionary dynamics and functional adaptation of the light-harvesting chlorophyll a/b-binding (<i>LHC</i>) superfamily in <i>A. annua</i>, with a focus on the early light‑induced protein (<i>ELIP</i>) subfamily. Comparative genomics of 24 plant species showed that the <i>LHC</i> superfamily recently expanded in the examined Asteraceae lineages through duplication events. In <i>A. annua</i>, 229 <i>LHC</i> genes identified from four haplotype genomes comprised 205 allelic and 24 haplotype-specific loci, with the <i>ELIP</i> subfamily expanding significantly via tandem duplication. Notably, compared to non-Asteraceae plants, <i>ELIPs</i> exhibited a uniform single-exon architecture, indicating it is a genomic feature unique to Asteraceae plants. Population genomics of 41 individuals showed dynamic copy number variations ranging from 1 to 4 copies per locus. Interestingly, a structurally disrupted <i>ELIP</i> allele remained transcriptionally active and produced long aberrant transcripts, showing that this subfamily is still actively evolving. Under UV-B stress, <i>AaELIP</i> loci showed synchronized induction trend but differed in expression levels, suggesting a division into major and auxiliary roles within the expanded tandem cluster. Overall, while the response of <i>ELIPs</i> to light stress is evolutionarily conserved, this dramatic expansion and structural streamlining of <i>AaELIPs</i> may represent a key evolutionary adaptation that enhances the plant’s ability to cope with intense light and radiation stress.</p> Conclusions <p>Collectively, this study demonstrates a significant expansion of the <i>LHC</i> superfamily in <i>A. annua</i>, especially within the <i>ELIP</i> subfamily, as well as its robust response to UV-B treatment, underscoring the essential role of <i>ELIPs</i> in mediating light stress responses. These findings provide a valuable foundation for future research to uncover the molecular mechanisms underlying <i>A. annua</i>’s adaptation to complex light environments.</p>

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Tandem duplication-driven expansion and UV-B stress adaptation of the LHC gene family in Artemisia annua L.

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年6月29日

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  • Xiaoxia Ding,
  • Danchun Zhang,
  • Siyu Zhao,
  • Shengye Bao,
  • Rongrong Zou,
  • Jieting Chen,
  • Lu Gong,
  • He Su,
  • Qiong Luo,
  • Hengyu Pan,
  • Lizhi Wang,
  • Shilin Chen,
  • Zhihai Huang,
  • Baosheng Liao

摘要

Background

Artemisia annua L., is the primary natural source of the antimalarial drug artemisinin. In nature, fluctuating light is a major environmental stress that affects plant growth and artemisinin biosynthesis. Although the light-harvesting chlorophyll a/b-binding (LHC) superfamily plays a key role in mediating plant responses to fluctuating light, systematic research of this gene family in A. annua has not yet been conducted, limiting our understanding of light adaptation in this medicinally important species.

Results

This study investigated the evolutionary dynamics and functional adaptation of the light-harvesting chlorophyll a/b-binding (LHC) superfamily in A. annua, with a focus on the early light‑induced protein (ELIP) subfamily. Comparative genomics of 24 plant species showed that the LHC superfamily recently expanded in the examined Asteraceae lineages through duplication events. In A. annua, 229 LHC genes identified from four haplotype genomes comprised 205 allelic and 24 haplotype-specific loci, with the ELIP subfamily expanding significantly via tandem duplication. Notably, compared to non-Asteraceae plants, ELIPs exhibited a uniform single-exon architecture, indicating it is a genomic feature unique to Asteraceae plants. Population genomics of 41 individuals showed dynamic copy number variations ranging from 1 to 4 copies per locus. Interestingly, a structurally disrupted ELIP allele remained transcriptionally active and produced long aberrant transcripts, showing that this subfamily is still actively evolving. Under UV-B stress, AaELIP loci showed synchronized induction trend but differed in expression levels, suggesting a division into major and auxiliary roles within the expanded tandem cluster. Overall, while the response of ELIPs to light stress is evolutionarily conserved, this dramatic expansion and structural streamlining of AaELIPs may represent a key evolutionary adaptation that enhances the plant’s ability to cope with intense light and radiation stress.

Conclusions

Collectively, this study demonstrates a significant expansion of the LHC superfamily in A. annua, especially within the ELIP subfamily, as well as its robust response to UV-B treatment, underscoring the essential role of ELIPs in mediating light stress responses. These findings provide a valuable foundation for future research to uncover the molecular mechanisms underlying A. annua’s adaptation to complex light environments.